JP4230210B2 - Optical reader - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an optical reader. More specifically, the present invention relates to an improvement in the structure of an optical reading apparatus that captures an image by irradiating a subject such as a card, a check, or a passbook with light.
[0002]
[Prior art]
2. Description of the Related Art An optical reader that irradiates a subject with light and collects reflected light on a light receiving element to capture an image is used (for example, see Patent Document 1). For example, in a device that reads a barcode, a character, or the like, it is common to use a light source that emits infrared light to separate dirt or a read character from the background. Also, depending on conditions such as the type of ink used for reading characters, the color of ink used for the background of reading characters, and the use of optical readers, the use of light other than infrared light may be suitable. There are various reading devices such as one using a red LED and one using a white fluorescent tube.
[0003]
Among these, when a red LED is used, the red LED itself is inexpensive and the cost of the apparatus is lower than that of a fluorescent tube. However, red may be a dropout color and red characters may not be read. For this reason, when a red LED cannot be used in this way, a reading apparatus using a white fluorescent tube with little influence of dropout color has been provided.
[0004]
In recent years, white LEDs have been manufactured and applied to optical products, and readers using white LEDs instead of white fluorescent tubes have also been made. White LEDs have high brightness and are easy to achieve downsizing. Therefore, in these respects, white LEDs are suitable as light sources in optical readers, but they are still expensive and difficult to use as many as cheap red LEDs. is there.
[0005]
[Patent Document 1]
JP-A-6-318734 [0006]
[Problems to be solved by the invention]
However, since a plurality of red and white LEDs are arranged at intervals, the light that irradiates the subject is not a single uniform light beam as in a fluorescent tube, but only the LED portion has a bright illuminance unevenness. Become.
[0007]
SUMMARY OF THE INVENTION An object of the present invention is to provide an optical reading apparatus that is inexpensive while using an LED as a light source, and that reduces or eliminates uneven illuminance.
[0008]
[Means for Solving the Problems]
In order to achieve this object, the invention described in claim 1 is directed to an optical reader that irradiates a subject with light from a light source and focuses reflected light from the subject onto a light receiving element via a lens. An illuminating device including a light source for irradiation includes a plurality of LEDs, an LED substrate in which the LEDs are arranged at intervals, a case for fixing the LED substrate, and a diffused irradiation that is arranged in the case and irradiated by the LEDs. And a cylindrical lens for converging light into parallel light, and the LED substrate is formed with lands formed around the LED through an insulating portion to reflect light emitted from the LED. It is.
[0009]
In this optical reader, the land formed on the LED substrate reflects the light emitted by the LED, so that more light can be emitted to the subject. For this reason, it is possible to maintain or reduce the number of LEDs while securing a necessary and sufficient amount of light as an optical reading device, thereby reducing the cost. In this case, although the LEDs are arranged at intervals, the illuminance unevenness may occur by further reducing the number of points, but according to the land formed on the LED substrate, the light and darkness is reflected when reflecting the light. Unevenness can be reduced or eliminated by reducing the bias.
[0010]
The invention described in claim 2 is characterized in that the land is formed of solder. With solder, lands can be formed at low cost. In addition, lands having various shapes can be formed according to the specification, the number of installation points, the arrangement, and the like of the LED.
[0011]
The invention described in claim 3 is characterized in that the LED is a white LED. A white LED is suitable as a light source for an optical reader because it has high brightness and can easily be miniaturized. In addition, according to the present invention, it is possible to maintain or reduce the number of LEDs while securing a necessary and sufficient amount of light by the land, so that the cost can be reduced.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the configuration of the present invention will be described in detail based on an example of an embodiment shown in the drawings.
[0013]
1 to 4 show an embodiment of the present invention. The optical reader 1 according to this embodiment irradiates a subject 4 with light emitted from a light source 3, collects the reflected light on a light receiving element 6 through a lens 5, and captures an image of the subject 4.
[0014]
The illuminating device 11 provided with the light source 3 includes a plurality of white LEDs (hereinafter referred to as “white LEDs 3” in the description of the present embodiment) as the light sources 3, and an LED substrate 7 in which the white LEDs 3 are arranged at intervals. A case 2 for fixing the LED substrate 7 and a cylindrical lens 8 arranged in the case 2 for converging diffusing irradiation light emitted from the white LED 3 into parallel light are provided (see FIG. 3). The LED substrate 7 is formed with lands 9 formed around the white LEDs 3 through the insulating portion 10 and reflecting the light emitted from the white LEDs 3 (in FIG. 1, the lands 9 are hatched). Shown). Furthermore, the optical reading device 1 of the present embodiment includes a glass plate 12 that transmits the light emitted from the white LED 3 and a reflecting mirror 13 that changes the direction of the reflected light reflected by the upper surface 4a of the subject 4 to a direction in which the lens 5 is located. The lens 5 that collects the reflected light reflected by the reflecting mirror 13 and the CCD 6 that is a light receiving element that converts the light from the lens 5 into an electrical signal are provided. The subject 4 capable of capturing an image is, for example, a card, a check, a bankbook, or the like.
[0015]
In the present embodiment, a white LED 3 that can obtain high luminance is used as a light source. However, since the white LED 3 is generally expensive, it is preferable that the number of points is as small as possible within a range in which a necessary and sufficient amount of light can be obtained to reduce the cost. In the present embodiment, a plurality of, for example, six white LEDs 3 are equally arranged on the LED substrate 7 in a line, and a light reflecting portion that reflects light emitted from the white LEDs 3 around the white LEDs 3 (in the present specification, this is referred to as “ The land is designated by the reference numeral 9) to compensate for the amount of light (see FIG. 1). The land 9 is preferably made of a highly reflective material that can reflect light more efficiently. In the present embodiment, the land 9 is formed by forming a pattern using solder which can obtain a high reflectance and is low in cost. According to the solder, a higher reflectance can be achieved than when, for example, a white resist is used as the reflecting material. Further, although the white resist is difficult to make as compared with the land 9, in this embodiment, since the land 9 is formed using solder, the operation becomes relatively easy. In addition, when a relatively soft solder is used, it is easy to form the white LED 3 in various shapes according to the specifications, the number of installation points, the arrangement, and the like. The surface shape of the land 9 may be, for example, a concave shape that easily converges reflected light. However, when solder is selected as the material of the land 9 as described above, it is necessary to provide an insulating portion 10 between the white LED 3 and the land 9 in order to maintain insulation with the white LED 3. For example, in the case of the present embodiment, a gap having a certain width or more is formed between the white LED 3 and the land 9 to form the insulating portion 10 (see FIG. 1).
[0016]
The glass plate 12 is fixed to a medium guide portion 2a outside the case 2 formed to protrude toward the medium path so as to be positioned between the white LED 3 and the subject 4. The reflecting mirror 13 is affixed to the upper part 16 a of the bracket 16 fixed with screws 15 in the case 2. The upper portion 16a of the bracket 16 is bent at an appropriate angle toward the lens 5 so as to direct the reflected light from the medium upper surface 4a toward the lens 5. The illumination device 11 is fixed to the case 2 by a holder 17. The holder 17 is fixed to the inside of the case 2 of the optical reader 1 with a screw 14 (see FIG. 2). A stop 23 for reducing the amount of reflected light is provided in front of the lens 5.
[0017]
The control device of the optical reader 1 controls an image signal from the CCD 6, and includes an amplifier 18, an A / D (analog / digital) converter 19, a shading processing circuit 20, a halftone processing circuit 21, and The white reference memory 22 is used (see FIG. 4). The shading processing circuit 20 determines the image signal from the A / D converter 19 based on the white reference level in the white reference memory 22, and shades a portion having a higher reflectance than white that exceeds the white reference level as white. Make corrections. The halftone processing circuit 21 performs pseudo halftone processing (binarization processing) and moire removal. The white reference memory 22 stores a white reference level corresponding to shading by the white LED 3. In the present embodiment, a line CCD is used as the CCD 6.
[0018]
The operation of the optical reading apparatus 1 of the present embodiment configured as described above will be described below.
[0019]
When the subject 4 passes through the medium path and is conveyed to the vicinity of the medium guide portion 2a, a sensor (not shown) detects the subject 4. When receiving this detection signal, the white LED 3 emits light.
[0020]
Irradiation light from the white LED 3 passes through a condenser lens (not shown) and a glass plate 12 provided at the lower end of the illumination device 11 and is reflected by the medium upper surface 4a. The reflected light is reflected by the reflecting mirror 13 and then enters the CCD 6 along the optical axis of the lens 5 to be converted into an electrical signal. The image signal converted by the CCD 6 is amplified by the amplifier 18, A / D converted by the A / D converter 19, and shading corrected by the shading processing circuit 20. The image signal from the shading processing circuit 20 is subjected to pseudo halftone processing (binarization processing) and moire removal by the halftone processing circuit 21. As a result, images such as ink characters and bar codes formed on the medium upper surface 4a are read and taken in as data.
[0021]
The above-described embodiment is an example of a preferred embodiment of the present invention, but is not limited thereto, and various modifications can be made without departing from the scope of the present invention. For example, in the present embodiment, the preferred optical reading device 1 using the white LED 3 as the light source is shown, but an LED other than white may be used.
[0022]
Moreover, although what was formed with the solder as the land 9 was demonstrated, this is only a suitable example, You may form the land 9 with reflective materials, such as other materials and materials, for example, a mirror.
[0023]
【The invention's effect】
As is clear from the above description, according to the optical reading device of the first aspect, the land formed on the LED substrate reflects the light emitted from the LED, so that the subject can be irradiated with more light. For this reason, it is possible to reduce the number of LEDs while securing a necessary and sufficient amount of light as an optical reading device, and it is possible to reduce the cost.
[0024]
According to the optical reader of claim 2, the land can be formed with solder at a low cost. In addition, lands having various shapes can be formed according to the specification, the number of installation points, the arrangement, and the like of the LED.
[0025]
Further, according to the optical reader of the third aspect, since the white LED is used, it is possible to obtain a light source with high brightness. In addition, it is possible to maintain or reduce the number of LEDs while securing a necessary and sufficient amount of light by the land, so that the cost can be reduced. Therefore, it can be made inexpensive while using a white LED.
[Brief description of the drawings]
FIG. 1 is a view showing an embodiment of the present invention, and shows an LED substrate in which lands are formed around white LEDs via an insulating portion.
FIG. 2 is a plan view of the optical reader according to the present embodiment.
3 is a cross-sectional view taken along line III-III of the optical reading device shown in FIG.
FIG. 4 is a block diagram illustrating a configuration of a control device.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Optical reader 2 Case 3 White LED (light source)
4 Subject 5 Lens 6 Light-receiving element 7 LED substrate 8 Cylindrical lens 9 Land 10 Insulating part 11 Illumination device

Claims (3)

In an optical reader that irradiates a subject with light from a light source and focuses reflected light from the subject onto a light receiving element via a lens, an illumination device including the light source that irradiates the subject includes a plurality of LEDs and The LED board having the LEDs arranged at intervals, a case for fixing the LED board, and a cylindrical lens arranged in the case for converging the radiated irradiation light emitted from the LED into parallel light. The optical reading device is characterized in that lands are formed on the LED substrate through insulating portions around the LEDs to reflect light emitted from the LEDs. 2. The optical reader according to claim 1, wherein the land is formed of solder. The optical reader according to claim 1, wherein the LED is a white LED.

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